|
|
Study of low-temperature plasma products using mass spectrometry and their relation to thin film chemistry
Maršálek, Blahoslav ; Bránecký, Martin (referee) ; Čech, Vladimír (advisor)
The aim of this thesis was to analyse and interpret the spectra of tetravinylsilane as a function of plasma discharge power in order to find a relationship between plasma products, layer deposition and thin film chemistry. Another objective was to carry out a literature search in the field of plasma-enhanced chemical vapour deposition (PECVD) and mass spectrometry. Low temperature organosilicate-based plasma technology enables the synthesis of specific materials with controlled chemical and physical properties. The targeted synthesis of surfaces with controlled properties is determined by the atomic and molecular processes in the plasma, which are responsible for building the chemical structure and the resulting material in the form of a thin film. In this work, mass spectrometry has been used to detect and quantify the particles produced in the PECVD process, which is one of the methods that allow the characterization and identification of plasma products. Analysis of the mass spectra revealed that the molecules responsible for the growth of the layer contain carbon and silicon. The deposition rate determined by in situ spectroscopic ellipsometry correlates quantitatively with the flux of carbon and silicon particles that are chemisorbed on the film surface. The ratio of carbon and silicon deposited on the surface also correlates strongly with the C/Si flux ratio of the power driven plasmas. The contribution of silicon-containing particles as building blocks to the film growth decreases with increasing power and accounts for 20% (2 W), 5% (10 W) and only 1% (75 W) of the total chemisorbed fraction. This ratio between bound silicon containing particles and carbon particles affects the elemental composition and chemical structure of the deposited layers. The relationships between plasmachemical processes and particle adhesion on the surface are quite complex. The adhesion of silicon particles first increases sharply to a maximum at 25 W and then gradually decreases, which is characteristic of the so-called precursor-deficient PECVD. Similarly, the concentration of vinyl groups incorporated into the deposited layer and the fraction of sp2 hybridization of carbon correlate with the particle fluxes of the corresponding plasma. This work has demonstrated that mass spectroscopy is a suitable method for the study of plasmachemical deposition from the gas phase (PECVD). PECVD technology is promising for the deposition of silicon-containing layers, which is technologically applicable in many directions of materials research.
|
|
|
Chemical analysis of a-CSi:H and a-CSiO:H films
Olivová, Lucie ; Franta, Daniel (referee) ; Čech, Vladimír (advisor)
Plasma-enhanced chemical vapor deposition is a promising technology for the preparation of materials in the form of thin films with controlled physical-chemical properties, which can be affected by changing input precursors or deposition conditions as needed. In this thesis, plasma nanotechnology was used to synthesize thin films on silicon wafers. Tetravinylsilane was chosen as a precursor for the synthesis of the films. In addition to pure tetravinylsilane, mixtures of tetravinylsilane with argon and mixtures of tetravinylsilane with oxygen were also used as input precursors for film deposition, in different proportions of the individual component in the deposition mixture. Using chemical analyses, specifically infrared spectroscopy, photoelectron spectroscopy and selected ion techniques, the chemical structure of the prepared films was examined in detail and the dependence of this structure on deposition conditions and input precursors was studied. This thesis confirms, that by changing effective power supplied to the plasma discharge and selecting different input precursors, it is possible to control chemical structure, and thus the properties of the prepared nanolayers.
|
|
| |
|
|
Synthesis of low-crosslinked polymers by plasma polymerization
Kuchtová, Štěpánka ; Bránecký, Martin (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with plasma enhanced chemical vapour deposition (PECVD), specifically plasma polymerisation, which has been used for the synthesis of low density crosslinked polymer thin films. Organosilicon thin films were deposited on a silicon substrate by radio frequency (RF) capacitively coupled plasma in a deposition chamber. Spectroscopic ellipsometry was used to determine the layer thickness and its optical properties. The chemical structure of the layers was investigated by Fourier transform infrared spectroscopy and the mechanical properties were investigated by nanoindentation. The effect of power and self-bias (USB) on the chemical structure, mechanical and optical properties of the as-prepared layers, which are related to the crosslinking density, was investigated in the context of achieving low crosslinking density of the material. Low crosslinked plasma polymers were synthesized at a self-bias level of 1 V, which corresponds to an approximate RF power of 0,1 W. This material can be characterized by a density of 1, 2 g·cm-3 an elastic modulus of 4 GPa, a hardness of 0,04 GPa and a refractive index of 1.53 at 633 nm (He-Ne laser wavelength). Infrared spectroscopy confirmed that this plasma polymer is composed of a carbon network with fewer embedded silicon atoms and, in particular, the highest concentration of vinyl groups compared to plasma polymers prepared at higher powers.
|
|
|
Study of low-temperature plasma products using mass spectrometry and their relation to thin film chemistry
Maršálek, Blahoslav ; Bránecký, Martin (referee) ; Čech, Vladimír (advisor)
The aim of this thesis was to analyse and interpret the spectra of tetravinylsilane as a function of plasma discharge power in order to find a relationship between plasma products, layer deposition and thin film chemistry. Another objective was to carry out a literature search in the field of plasma-enhanced chemical vapour deposition (PECVD) and mass spectrometry. Low temperature organosilicate-based plasma technology enables the synthesis of specific materials with controlled chemical and physical properties. The targeted synthesis of surfaces with controlled properties is determined by the atomic and molecular processes in the plasma, which are responsible for building the chemical structure and the resulting material in the form of a thin film. In this work, mass spectrometry has been used to detect and quantify the particles produced in the PECVD process, which is one of the methods that allow the characterization and identification of plasma products. Analysis of the mass spectra revealed that the molecules responsible for the growth of the layer contain carbon and silicon. The deposition rate determined by in situ spectroscopic ellipsometry correlates quantitatively with the flux of carbon and silicon particles that are chemisorbed on the film surface. The ratio of carbon and silicon deposited on the surface also correlates strongly with the C/Si flux ratio of the power driven plasmas. The contribution of silicon-containing particles as building blocks to the film growth decreases with increasing power and accounts for 20% (2 W), 5% (10 W) and only 1% (75 W) of the total chemisorbed fraction. This ratio between bound silicon containing particles and carbon particles affects the elemental composition and chemical structure of the deposited layers. The relationships between plasmachemical processes and particle adhesion on the surface are quite complex. The adhesion of silicon particles first increases sharply to a maximum at 25 W and then gradually decreases, which is characteristic of the so-called precursor-deficient PECVD. Similarly, the concentration of vinyl groups incorporated into the deposited layer and the fraction of sp2 hybridization of carbon correlate with the particle fluxes of the corresponding plasma. This work has demonstrated that mass spectroscopy is a suitable method for the study of plasmachemical deposition from the gas phase (PECVD). PECVD technology is promising for the deposition of silicon-containing layers, which is technologically applicable in many directions of materials research.
|
|
|
Synthesis of low-crosslinked polymers by plasma polymerization
Kuchtová, Štěpánka ; Bránecký, Martin (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with plasma enhanced chemical vapour deposition (PECVD), specifically plasma polymerisation, which has been used for the synthesis of low density crosslinked polymer thin films. Organosilicon thin films were deposited on a silicon substrate by radio frequency (RF) capacitively coupled plasma in a deposition chamber. Spectroscopic ellipsometry was used to determine the layer thickness and its optical properties. The chemical structure of the layers was investigated by Fourier transform infrared spectroscopy and the mechanical properties were investigated by nanoindentation. The effect of power and self-bias (USB) on the chemical structure, mechanical and optical properties of the as-prepared layers, which are related to the crosslinking density, was investigated in the context of achieving low crosslinking density of the material. Low crosslinked plasma polymers were synthesized at a self-bias level of 1 V, which corresponds to an approximate RF power of 0,1 W. This material can be characterized by a density of 1, 2 g·cm-3 an elastic modulus of 4 GPa, a hardness of 0,04 GPa and a refractive index of 1.53 at 633 nm (He-Ne laser wavelength). Infrared spectroscopy confirmed that this plasma polymer is composed of a carbon network with fewer embedded silicon atoms and, in particular, the highest concentration of vinyl groups compared to plasma polymers prepared at higher powers.
|
|
|
Chemical analysis of a-CSi:H and a-CSiO:H films
Olivová, Lucie ; Franta, Daniel (referee) ; Čech, Vladimír (advisor)
Plasma-enhanced chemical vapor deposition is a promising technology for the preparation of materials in the form of thin films with controlled physical-chemical properties, which can be affected by changing input precursors or deposition conditions as needed. In this thesis, plasma nanotechnology was used to synthesize thin films on silicon wafers. Tetravinylsilane was chosen as a precursor for the synthesis of the films. In addition to pure tetravinylsilane, mixtures of tetravinylsilane with argon and mixtures of tetravinylsilane with oxygen were also used as input precursors for film deposition, in different proportions of the individual component in the deposition mixture. Using chemical analyses, specifically infrared spectroscopy, photoelectron spectroscopy and selected ion techniques, the chemical structure of the prepared films was examined in detail and the dependence of this structure on deposition conditions and input precursors was studied. This thesis confirms, that by changing effective power supplied to the plasma discharge and selecting different input precursors, it is possible to control chemical structure, and thus the properties of the prepared nanolayers.
|
|
| |
guest ::
